The Israeli Mossad(Not Mosad) is the nation's secret intelligence agency, like the US's CIA or the UK's MI6(SIS). When the Mossad agents use a .22LR it's for close range assassins. The covert ops use a surpressed .22LR target pistol or small revolver then fire several rounds at the head or face.
They may also use other firearms or weapons as required. Intel officers or spec ops often use "sterile" weapons or firearms they can deny. A German agent may use a Uzi with Canadian army 9mmNATO ammunition for example. Or a French operative may use a SIG Sauer P220 .45acp with American 230gr milspec ammunition.